An Institute of Professional Engineers (IPENZ) investigation into Christchurch complaints against Earthquake Commission (EQC) engineer Graeme Robinson has been escalated into a full inquiry.

The complaints deal with Robinson's alleged arrogant manner and inadequate "subsequent reports" to EQC and a claim he breached the IPENZ code of ethics.

A Press investigation over several months into assessments conducted by Robinson uncovered nearly 50 cases where homeowners were unhappy with Robinson, with many complaining to EQC.

He has done over 2000 assessments in Christchurch. He was named in a parliamentary select committee hearing earlier this month.

The IPENZ inquiry will consider seven formal complaints made to it but The Press understands IPENZ has several further complaints pending, one as recent as this week.

Robinson is a consultant to EQC and is provided with a car, accommodation and airfares for his role in Christchurch.

Because of the controversy, he has been removed from the frontline by EQC and is now training engineers and reviewing other engineers' assessments.

In a response to the seven complainants, IPENZ said their complaints would now be reviewed collectively by an investigating committee.

Under the IPENZ complaints process, a complaints research officer is first appointed to make a recommendation on whether a fuller investigation is warranted.

The officer's report is considered by an adjudicator who makes a final decision on whether an investigating committee is set up.

In Robinson's case the adjudicator, Jeff Jones, "reluctantly" decided to upscale the inquiry because of the number of complaints, their consistent theme and publicity in the media.

Jones noted the number of complaints to IPENZ were relatively small given the number of assessments done by Robinson and the encouragement in social media for homeowners to complain.

"Of concern is the degree of evidence some of Mr Robinson's encounters have been brief and may not have been sufficiently careful.

"Whether that insufficiency is of a degree warranting a description of negligence is an issue," Jones said.

He recognised Robinson was an expert in earthquake damage and noted a paper Robinson presented to an EQC seminar in 2010. The paper commented on "a propensity" of some to claim for earthquake damage when the damage was pre-existing, sometimes because of foundation movement, "indicating inadequate geotechnical assessment" before the structure was built.

The paper also highlighted homeowners claiming for reinstatement "to current standards" when the structure did not meet the applicable standard when built.

Jones said he believed it was appropriate for EQC to employ Robinson, particularly when a suspicion existed the homeowner was making the sort of claims referred to in Robinson's paper.

Robinson's initial response to the complaints was his inspections were likely not full inspections; in most cases questions had already been raised by other EQC staff; and engineers used by the homeowners were less experienced than he was and were doing preliminary reports.

Jones said the eight complaints to IPENZ could not be considered widespread dissatisfaction with Robinson and complaints about his "verbal demeanour" was a matter for his employer rather than IPENZ.

"Plain descriptions" by Robinson under pressure from questioning by the complainants could have been misinterpreted as "arrogance" because "the answer he gave was not perhaps the one they wanted to hear".

The outcome of the investigation could well be the complainants had chosen to discredit the messenger of "unpalatable" results, Jones said.

EQC was asked if the escalation by IPENZ had changed Robinson's status at EQC but a spokesman said all staff dealing with the matter were on leave.